Searching for Life around the Stars

BU researcher studies M Dwarfs for clues

During the summer months, BU Today is revisiting some of the past year’s favorite stories. This week, we feature scientific research.

To the epic search for life on other planets, Mark Veyette brings some of science’s most formidable technology: 300-pound infrared telescopes in Hawaii. The supercomputer center BU helped create in Holyoke, Mass.

And his cell phone.

Explanation to come about how that last one aids Veyette’s research into M dwarf stars, the most common star type in our galaxy. M dwarfs are smaller, cooler, and fainter than the sun, and Veyette (GRS’15,’19) is trying to determine their chemical composition and that of their atmospheres. This, in turn, could shed light on the composition of the dwarfs’ orbiting planets—hinting at whether those planets could sustain life.

Veyette has used a telescope at Hawaii’s Keck Observatory, but has managed just one trip there. The last time he used the heavily booked scope, he had to do it remotely from a room at Yale (BU’s remote observing room is awaiting approval to operate the Keck scope). Stargazing occupies just a fraction of his research hours, though, which mostly involve running computer models of M dwarfs through the Massachusetts Green High Performance Computing Center (MGHPCC) in Holyoke.

“I’ve used my phone before to submit quick jobs” to MGHPCC, says Veyette, one of several graduate students working with Philip Muirhead, a College of Arts & Sciences assistant professor of astronomy.

But phone and laptop are no substitute for the computing brains at the MGHPCC. “These are very complex models that take into account a lot of physics,” he says. “They’re trying to model essentially everything that is going on in the atmosphere of a star.…We really need that massive computing power to handle it all.”

The models of the stars that the Holyoke center’s computers create can be compared to data Veyette collects by gazing at the actual dwarfs. He seeks the model that best matches the data, then uses that model to assign properties to the star—“this star must have this temperature, must have this much iron in it, this much oxygen.”

Stars and planets form from the same cloud of gas and dust that collapses down; stars are mostly hydrogen and helium while rocky planets like Earth are made up of heavier elements. “If a star is particularly rich in heavier things like oxygen, magnesium, and silicon, it might be easier to form Earth-like planets around that star,” he says, “because you have more planet-building material in the gas cloud already.”

Proxima Centauri, the nearest known star to our sun, is the kind of star that BU researchers are studying for signs of extraterrestrial life. Photo by ESA Hubble/NASA

A higher-density, rockier planet like ours theoretically could support life. “If it’s a very low-density, puffy sort of planet, then it’s more like a Neptune-type planet, which is just a gas giant. There’s no real solid surface that could support life,” Veyette says. Of course, it’s also theoretically possible that a planet could support something that’s not life as we know it. But for now, “we only have one example of a planet with life on it, and that’s Earth.”

Veyette is also developing a technique to estimate dwarfs’ ages that Muirhead says will be transformative.

“With a way to measure star ages, we can begin to study how M dwarfs and their planets change over time, which is a missing piece of the exoplanet puzzle,” Muirhead says. (Exoplanets are those that circle stars outside our solar system.)

Much of the work by Muirhead and his research team is in anticipation of NASA’s Transiting Exoplanet Survey Satellite (TESS), launching next year to hunt for exoplanets. Muirhead leads the group determining the stars for study by TESS.

Take away the ET thrill of possible life out there and we’d still be studying M dwarfs, which comprise 70 percent of stars in our galaxy, Veyette says. But the search for extraterrestrial life was a big prod to his doing this research. “I’m interested in both the stellar physics behind everything, but also its applications to exoplanets,” he says.

Astronomy came to him as an undergrad at the University of Washington. Intent on both a computer science major and an MBA, “just for a sort of general science credit,” he took “an astronomy class with an amazing professor,” who laid out for him the importance of computers in astronomical research. He was hooked on outer space.

As for the chances we’ll find life by studying M dwarfs: “Predicting scientific discovery is a bit like predicting the stock market,” Muirhead says. “That said, I suspect we will find some evidence for life on other planets within my lifetime. Astronomers are largely motivated by optimism about discovery, so I guess I’m optimistic by nature.”